U.S. patent application number 11/300412 was filed with the patent office on 2006-08-03 for optical fiber cable.
This patent application is currently assigned to Hitachi Cable, Ltd.. Invention is credited to Yoshihiro Kodaka, Takahiro Sato, Tatsuo Teraoka.
Application Number | 20060171644 11/300412 |
Document ID | / |
Family ID | 36756633 |
Filed Date | 2006-08-03 |
United States Patent
Application |
20060171644 |
Kind Code |
A1 |
Sato; Takahiro ; et
al. |
August 3, 2006 |
Optical fiber cable
Abstract
An optical fiber cable comprises optical fiber tapes, each of
which is composed of a plurality of optical fiber cores disposed in
parallel and connected by a joint member, and two or more pieces of
the optical fiber tapes are layered and accommodated in a sheath.
The optical fiber tape is provided with a concave portion between
adjacent optical fiber cores and a convex portion, and the two or
more pieces of the optical fiber tapes are layered by engaging the
concave portion and convex portion to be accommodated in the
sheath.
Inventors: |
Sato; Takahiro; (Hitachi,
JP) ; Teraoka; Tatsuo; (Hitachi, JP) ; Kodaka;
Yoshihiro; (Kitaibaraki, JP) |
Correspondence
Address: |
MCGINN INTELLECTUAL PROPERTY LAW GROUP, PLLC
8321 OLD COURTHOUSE ROAD
SUITE 200
VIENNA
VA
22182-3817
US
|
Assignee: |
Hitachi Cable, Ltd.
Tokyo
JP
|
Family ID: |
36756633 |
Appl. No.: |
11/300412 |
Filed: |
December 15, 2005 |
Current U.S.
Class: |
385/114 |
Current CPC
Class: |
G02B 6/4433 20130101;
G02B 6/4403 20130101; G02B 6/4422 20130101; G02B 6/4411
20130101 |
Class at
Publication: |
385/114 |
International
Class: |
G02B 6/44 20060101
G02B006/44 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 28, 2005 |
JP |
2005-021246 |
Claims
1. An optical fiber cable, comprising: an optical fiber tape
comprising a plurality of optical fiber cores disposed in parallel
and a joint member for connecting a plurality of the optical fiber
cores; and a sheath for accommodating two or more pieces of the
optical fiber tapes; wherein the optical fiber tape is provided
with a concave portion between adjacent optical fiber cores and a
convex portion, and the two or more pieces of the optical fiber
tapes are layered by engaging the concave portion and convex
portion.
2. The optical fiber cable, according to claim 1, wherein: the
optical fiber core comprises an optical fiber colored strand having
a colored layer as an outermost layer, and an over coating layer
formed on the optical fiber colored strand to have an outer
diameter of 0.4 mm or more.
3. The optical fiber cable, according to claim 1, wherein: one or
two tensile strength resistant members is accommodated in the
sheath.
4. An optical fiber cable, comprising: an optical fiber tape
comprising a plurality of optical fiber cores disposed in parallel
and a joint member for connecting a plurality of the optical fiber
cores; a sheath for accommodating two or more pieces of the optical
fiber tapes; and a supporting wire part comprises a supporting wire
and a supporting wire part sheath provided on an outer periphery of
the supporting wire, and the supporting wire part is connected to
the sheath via a neck portion continuously; wherein the optical
fiber tape is provided with a concave portion between adjacent
optical fiber cores and a convex portion, and the two or more
pieces of the optical fiber tapes are layered by engaging the
concave portion and convex portion.
5. The optical fiber cable, according to claim 4, wherein: the
optical fiber core comprises an optical fiber colored strand having
a colored layer as an outermost layer, and an over coating layer
formed on the optical fiber colored strand to have an outer
diameter of 0.4 mm or more.
6. The optical fiber cable, according to claim 4, wherein: one or
two tensile strength resistant members is accommodated in the
sheath.
7. An optical fiber cable, comprising: an optical fiber tape
comprising a plurality of optical fiber cores disposed in parallel
and a joint member for connecting a plurality of the optical fiber
cores; a sheath for accommodating two or more pieces of the optical
fiber tapes; and a supporting wire part comprises a supporting wire
and a supporting wire part sheath provided on an outer periphery of
the supporting wire, and the supporting wire part is connected to
the sheath via a neck portion intermittently; wherein the optical
fiber tape is provided with a concave portion between adjacent
optical fiber cores and a convex portion, and the two or more
pieces of the optical fiber tapes are layered by engaging the
concave portion and convex portion.
8. The optical fiber cable, according to claim 7, wherein: the
optical fiber core comprises an optical fiber colored strand having
a colored layer as an outermost layer, and an over coating layer
formed on the optical fiber colored strand to have an outer
diameter of 0.4 mm or more.
9. The optical fiber cable, according to claim 7, wherein: one or
two tensile strength resistant members is accommodated in the
sheath.
Description
[0001] The present application is based on Japanese Patent
Application No. 2005-021246 filed on Jan. 28, 2005, the entire
contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] Field of the Invention
[0003] The present invention relates to optical fiber cable for
installation, which is installed in an underground conduit or
between ground electric poles and is drawn into a building, a
condominium, or a house from the electric pole, in more
particularly, to an optical fiber cable, in which layered optical
fiber tapes are accommodated in a sheath.
[0004] In recent years, an -optical fiber cable using an optical
fiber tape is used for the layout drawn into subscriber's residence
such as building, individual house, so as to realize a FTTH (Fiber
to The Home), namely a communication of ultrahigh speed and large
capacity for respective homes or offices.
[0005] FIG. 1 shows a configuration of a conventional optical fiber
cable, which is disclosed by Japanese Patent Laid-Open No.
2003-295011 (JP-A-2003-295011). In an optical fiber cable 100 shown
in FIG. 1, a pair of tensile strength resistant members 121
comprising a conductive metal wire or a non-conductive metal wire
such as glass fiber, plastic, etc. are provided along both sides of
two pieces of optical fiber tapes 112 that are layered. An optical
element part 118 comprises a pair of the optical fiber tapes 112
and the tensile strength resistant members 121 covered collectively
with a sheath 120 made of a thermoplastic resin such as
fire-resistant PE. In addition, a supporting wire part 119
comprises a supporting wire 126 made of a metal wire, e.g. a steel
wire, and a supporting wire part sheath 123 made of a thermoplastic
resin such as PVC, fire-resistant PE for covering the supporting
wire 126. The optical element part 118 and supporting wire part 119
are connected in parallel with each other by a constricted neck
portion 122. Further, a notch 124 for tearing up the optical fiber
cable 100 is provided on both of long side faces of the sheath 120
to take out the optical fiber tapes 112. Further, another
conventional optical fiber having a similar configuration is
disclosed by Japanese Patent Laid-Open No. 2004-061649
(JP-A-2004-061649).
[0006] However, when a stress occurs in a direction along side
surfaces of the long side of the sheath 120 in the optical fiber
cable 100 shown in FIG. 1, there is a disadvantage in that small
curves are produced in the optical fiber tapes 112, thereby
increasing an optical loss of the optical fiber.
SUMMARY OF THE INVENTION
[0007] Accordingly, for solving the above problem, it is an object
of the present invention to provide an optical fiber cable in which
the increase of an optical loss in the optical fiber can be
suppressed even if a stress is generated.
[0008] According to a feature of the present invention, an optical
fiber cable, comprises:
[0009] an optical fiber tape comprising a plurality of optical
fiber cores disposed in parallel and a joint member for connecting
a plurality of the optical fiber cores; and
[0010] a sheath for accommodating two or more pieces of the optical
fiber tapes;
[0011] wherein the optical fiber tape is provided with a concave
portion between adjacent optical fiber cores and a convex portion,
and the two or more pieces of the optical fiber tapes are layered
by engaging the concave portion and convex portion.
[0012] According to a second feature of the invention, the optical
fiber core- may comprise an optical fiber colored strand having a
colored layer as an outermost layer, and an over coating- layer
formed on the optical fiber colored strand to have an outer
diameter of 0.4 mm or more.
[0013] According to a third feature of the invention, it is
preferable that one or two tensile strength resistant members is
accommodated in the sheath.
[0014] According to a fourth feature of the invention, an optical
fiber cable, comprises:
[0015] an optical fiber tape comprising a plurality of optical
fiber cores disposed in parallel and a joint member for connecting
a plurality of the optical fiber cores;
[0016] a sheath for accommodating two or more pieces of the optical
fiber tapes; and
[0017] a supporting wire part comprises a supporting wire and a
supporting wire part sheath provided on an outer periphery of the
supporting wire, and the supporting wire part is connected to the
sheath via a neck portion continuously;
[0018] wherein the optical fiber tape is provided with a concave
portion between adjacent optical fiber cores and a convex portion,
and the two or more pieces of the optical fiber tapes are layered
by engaging the concave portion and convex portion.
[0019] it is preferable that a supporting wire part comprises a
supporting wire and a supporting wire part sheath provided on an
outer periphery of the supporting wire, and the supporting wire
part is connected to the sheath via a neck portion
continuously.
[0020] According to a fifth feature of the invention, an optical
fiber cable, comprises:
[0021] an optical fiber tape comprising a plurality of optical
fiber cores disposed in parallel and a joint member for connecting
a plurality of the optical fiber cores;
[0022] a sheath for accommodating two or more pieces of the optical
fiber tapes; and
[0023] a supporting wire part comprises a supporting wire and a
supporting wire part sheath provided on an outer periphery of the
supporting wire, and the supporting wire part is connected to the
sheath via a neck portion intermittently;
[0024] wherein the optical fiber tape is provided with a concave
portion between adjacent optical fiber cores and a convex portion,
and the two or more pieces of the optical fiber tapes are layered
by engaging the concave portion and convex portion.
[0025] According to the present invention, it is possible to
provide an effect that the increase of the optical loss in the
optical fiber can be suppressed and that a lateral pressure
resistance characteristics is excellent, in case where a stress
occurs in a direction along side surfaces of a long side of a
sheath in an optical fiber cable.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Next, preferred embodiment according to the present
invention will be explained in conjunction with appended drawings,
wherein:
[0027] FIG. 1 is a cross sectional view showing a conventional
optical fiber cable;
[0028] FIG. 2 is a cross sectional view showing an optical fiber
cable in a preferred embodiment according to the present
invention;
[0029] FIG. 3 is a cross sectional view showing an optical fiber
tape used for the optical fiber cable in the preferred embodiment
according to the present invention;
[0030] FIG. 4 is a cross sectional view showing an optical fiber
core used for the optical fiber cable in the preferred embodiment
according to the present invention;
[0031] FIGS. 5A and 5B are diagrams showing side views of the
optical fiber cable in the preferred embodiment according to the
present invention, wherein FIG. 5A is a side view of the optical
fiber in which neck portion is provided continuously and FIG. 5B is
a side view of the optical fiber in which neck portion is provided
intermittently;
[0032] FIG. 6 is a schematic diagram showing a method of conducting
a lateral pressure characteristic evaluation test; and
[0033] FIG. 7 is a graph showing a result of the lateral pressure
characteristic evaluation test.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0034] Next, the preferred embodiment according to the present
invention will be explained in conjunction with the appended
drawings.
[0035] FIG. 2 shows an optical fiber cable in a preferred
embodiment according to the present invention.
[0036] An optical fiber cable 1 in the preferred embodiment shown
in FIG. 2 is an optical fiber cable having a substantially
rectangular cross section. An optical fiber cable 1 comprises an
optical element part 18 and a supporting wire part 19.
[0037] In the optical element part 18, two pieces of optical fiber
tapes 12 are layered by engaging concave portions 29 and convex
portions 28, and tensile strength resistant members 21 are disposed
on both sides of the layered optical fiber tapes 12. The optical
fiber tapes 12 and tensile strength resistant members 21 are
covered with a sheath 20 collectively to be accommodated in the
sheath 20.
[0038] In the supporting wire part 19, a supporting wire part
sheath 23 is provided on an outer periphery of a supporting wire
26.
[0039] The optical element part 18 and supporting wire part 19 are
connected in parallel with each other by a constricted neck portion
22. Further, a notch 24 for tearing up the optical fiber cable 1 is
provided on both of long side faces of the sheath 20 to take out
the optical fiber tapes 12.
[0040] FIGS. 5A and 5B show side views of the optical fiber cable 1
in the embodiment according to the present invention, wherein FIG.
5A is a side view of the optical fiber in which the neck portion 22
is provided continuously and FIG. 5B is a side view of the optical
fiber in which the neck portions 22 are provided intermittently. As
shown in FIG. 5A, the supporting wire part 19 is connected to the
sheath 20 of the optical element part 18 via the neck portion 22
continuously. As shown in FIG. 5B, the supporting wire part 19 may
be connected to the sheath 20 via the neck portions 22
intermittently, namely slot portions 30 each having a width 12 are
provided between the neck portions 22 each having a width 11.
[0041] FIG. 3 shows an optical fiber tape 12 used for the optical
fiber cable 1 in the preferred embodiment according to the present
invention. An optical fiber tape 12 in the preferred embodiment
shown in FIG. 3 comprises a plurality of optical fiber cores 10
(the number of optical fiber cores 10 is four in FIG. 3) arranged
in parallel with each other and connected with a joint member 11.
The joint member 11 is provided such that the concave portion 29 is
formed between adjacent optical fiber cores 10. In FIG. 3, the
joint member 11 is provided only between the adjacent optical fiber
cores 10, however the present invention is not limited thereto. For
example, the joint member 11 may be provided to cover an outer
periphery of a plurality of the optical fiber cores 10. If the
concave portion 29 is formed between the adjacent optical fiber
cores 10, the configuration of the optical fiber tape 12 is not
limited.
[0042] For the optical fiber core 10, as shown in FIG. 2, an
optical fiber core with an increased diameter, in which an over
coating layer 13 is provided around a colored layer 14 to have an
outer diameter of 0.4 mm or more, may be preferably used. Since the
optical fiber core with an increased diameter is excellent in
operativity, such an optical fiber core is used for the optical
fiber cable for installation in the present invention. The optical
fiber tape comprising the optical fiber cores with the increased
diameter is suitable to produce the optical fiber tape 12 shown in
FIG. 3, since a groove between the adjacent optical fiber cores is
large.
[0043] The optical fiber cable in an embodiment according to the
present invention will be described in conjunction with the
appended drawings.
[0044] In the embodiment, as shown in FIG. 4, an optical fiber core
10 comprises an optical fiber glass part 17 having an outer
diameter of about 0.125 mm, an optical fiber strand primary coating
layer 16 and an optical fiber strand secondary coating layer 15,
each of which is composed of an ultraviolet curing resin for
covering the optical fiber glass part 17 to have an outer diameter
of about 0.245 mm. In addition, the optical fiber strand secondary
coating layer 15 is coated by a colored layer 14 composed of an
ultraviolet curing resin to have an outer diameter of about 0.255
mm, and further the colored layer 14 is coated by an over coating
layer 13 composed of an ultraviolet curing resin to have an outer
diameter of about 0.50 mm.
[0045] The optical fiber tape 12 in this embodiment comprises, as
shown in FIG. 3, the optical fiber cores 10 that are connected by a
joint member 11 composed of an ultraviolet curing resin. As to
regard an overall dimension of the optical fiber tape 12, a long
diameter is about 2.05 mm and a short diameter is about 0.52
mm.
[0046] In the optical fiber cable 1 of this embodiment, as shown in
FIG. 4, two pieces of the optical fiber tapes 12 are arranged so
that the concave portions 29 and convex portions 28 are engaged
with each other. A pair of tensile strength resistant members
(tension members) 21, each of which comprises galvanized steel wire
having a diameter of 0.4 mm, are disposed along both sides of the
optical fiber tapes 12. The optical fiber tapes 12 and tensile
strength resistant members 21 are jacketed collectively with a
sheath 20 comprising a low-density polyethylene resin, to provide
an optical element part 18. A supporting wire 26 comprising a
galvanized steel wire with a diameter of 2.3 mm is jacketed with a
supporting wire part sheath 23 comprising a low-density
polyethylene resin, to provide a supporting wire part 19. The
optical element part 18 and the supporting wire part 19 are
disposed in parallel with each other and connected with each other
by a constricted neck portion 22. In addition, on both of long side
faces of the sheath 20, a notch 24 is provided for tearing up the
optical fiber cable 1 for taking out the optical fiber tapes 12. A
total height of the optical fiber cable 1 is about 7 mm.
[0047] Next, a lateral pressure characteristic evaluation test for
an optical fiber cable was carried out. FIG. 6 shows a method of
conducting the lateral pressure characteristic evaluation test.
[0048] A cable 25 to be measured is sandwiched between lateral
pressure boards 27, and a load is applied thereto in a direction
indicated by an arrow of FIG. 6. This is a method of evaluating a
lateral pressure characteristic of the optical fiber cable by
measuring an increasing amount (dB) of an optical loss of the
optical fiber with increasing the load (N/100 mm) applied
thereto.
[0049] The lateral pressure characteristic evaluation test was
conducted by using a conventional optical fiber cable shown in FIG.
1 and an optical fiber cable according to the present invention
shown in FIG. 2 as the cable 25 to be measured.
[0050] FIG. 7 shows a result of the lateral pressure characteristic
evaluation test. As shown in FIG. 7, as for the conventional
optical fiber cable, the optical loss is increased under a load of
2500 N/100 mm. As for the optical fiber cable of the present
invention, the optical loss is increased under a load of 3500 N/100
mm. As described above, it was confirmed that the optical fiber
cable of the present invention is excellent in the lateral pressure
resistance characteristic comparing with the conventional optical
fiber cable.
[0051] Although the invention has been described with respect to
specific embodiment for complete and clear disclosure, the appended
claims are not to be thus limited but are to be construed as
embodying all modification and alternative constructions that may
be occurred to one skilled in the art which fairly fall within the
basic teaching herein set forth.
* * * * *